St. John’s faces a season full of challenges over the next four months. Thursday’s might be the biggest of them all. The Red Storm — with a rotation just seven players deep — will take on the top-ranked team in the country, the Kentucky Wildcats, at Lexington’s famed Rupp Arena. And now they’ll do it without their head coach. As first reported by ESPN’s Andy Katz late Monday night, Steve Lavin has decided to take an indefinite leave of absence from coaching St. John’s as he continues to recuperate from his Oct. 6 prostate cancer surgery.